300BlkTalk

FYI I am in the process of making a few hundred 300 BLK cases right now. They are cut, deprimed and resized. I am about half way through trimming to length.

When I am done I will load a batch of ammo with my home cut brass and see how they go. Some of the cases have military crimps on them so I might have to swage a few.

Within the first 100 rounds I should know if I have issues or not...

One question...how bad does 300BLK stretch when firing? Not a lot (maybe 10 or 15 cases) were cut a little short...after forming they are maybe .001 short of a factory case...but aside from that no issues.

“Shorter than factory” has no meaning, but even a few thousandths short of minimum spec won’t create problems.

Unless it’s a pretty hot load they won’t stretch at all, in fact they are more likely to shrink on the first firing. From there it will depend on how you resize them, and the load.

Nothing wrong with converting brass. I've not converted 556 brass myself, but before properly headstamped cases were available and affordable, I had really good and really bad experiences with the quality of converted brass bought from folks on this forum.

A little off topic, but if you plan on training or taking classes, I recommed using properly head stamped cases. I took a class using converted brass and as the instructors loaded down our mags, they put my LC stamped 300blk rounds back in my partners LC 556 ammo bag. My partner didnt catch it until the next day and the instructor felt terrible because he did infact check the headstamp.

Those poo pooing the idea of making your own due to case neck thickness are usually holdovers from when it was the 300 whisper. The 300 Whisper was based on the .221 fireball being necked up and had a thinner neck. One of the main differences between the 300BLK and 300 whisper is that the 300BLK was specifically designed to be made from .223 brass meaning the chamber has been specifically designed for thicker case necks. This is also why it is OK to use 300 whisper ammo in the 300BLK but may cause problems using 300BLK ammo in 300 whispers.

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What's wrong with it? Eh, it's one of those things that (if you are a hobbyist who likes to make your own things) is something you can say you have done. I liked the IDEA of making my own brass but after the new wore off of it, I wished I had just bought pre-formed brass.

It's a bit tedious to do properly unless you sink a bunch of money into equipment. I got lazy and cut my brass to where I wouldn't have to trim it. The length came out right but the case necks were uneven and accuracy wasn't as good as properly trimmed brass. My formed cases will crack at the case mouth or shoulder after several reloadings so sorting carefully is always important.

Do not use 5.56 that has been fired multi-X. My buddy gave me some and I formed ~100 cases and they all broke on the first firing. After that I bought some 5.56 blanks to convert assuming that they had been fired with less pressure/stress on the brass. That's my theory and I'm sticking to it.

The abundance of once fired 5.56/.223 brass means we BLK guys can choose to make our own. So far, the quality of my efforts has been rewarding. Today, I just finished another 400+ that were made from a manufacturer's damaged brass. Many with good bullets pushed into the case. One batch was all FC 11, with primer in place. This last bunch also was primed, netting 300+ LC and 100+ miscellaneous primed cases. This is the last of the thousands we purchased to process 8 years ago. I think my little saw has cut about 3-4K so far, a new belt is needed.

I did try a new jig that works well, but I have had to fiddle with it to get it set up. Now I have to get back to finishing the freshening up of my 18' camp trailer and the down stairs bath remodel....arrrgh.

Sorry. I have not been online a lot since this original post. Since then I have formed around 500 pieces of BLK brass and for the most part they worked great. I've shot no less than 500 rounds on my own formed brass.

Here is my report on what has and hasn't worked.

In those 500ish pieces of brass I've had 3 or 4 that would not chamber. Yes, I found out for myself that this is a thing. I will eventually come up with a way to measure or whatever so I don't have to deal with working on 'bad' rounds that I just toss. That said, it might have been 5 pieces of brass total that were a problem. Not a bad ratio.

In the end, the ability to form brass from .223 is very attractive because that stuff is very plentiful.

I have not had to anneal my brass yet, but I could see the need for this eventually. As the metal gets work hardened it could present a problem especially if you are constantly belling your necks and so forth. I might touch up my brass some once I make more just because. I don't think this is absolutely necessary but hey, why not, especially if you are going to use the same brass over and over again. I just have to figure out how to do a lot of it for cheap. Please keep in mind that annealing is NOT mandatory. I am only considering it because I am a perfectionist.

Lee dies... they did not work for me. I have been using Lee for years but this is the first time I encountered a problem with the FLS die in 300 BLK. I use a Forster FLS die and the same brass worked flawlessly. No more neck tension problems etc... definitely a great upgrade is to use a better die. One thing that made me go 'dude I need to think about this' (regarding the die) was when I belled a case and my bullet fell right into the case with zero neck tension. Yes I formed the brass right. And right after that I took the same brass, formed it with a Forster and it had perfect neck tension and ran like a champ. It might have been just my die, but I got the problem solved and now it's in the rear view mirror.

Other than that the only other potential downside is just the time to set up and make brass. It's not some horrible thing by any means and I personally enjoy doing hands on projects, but from a sheer cost perspective I would have to check to see if off the shelf brass is any cheaper than forming your own.

In any case knowing HOW to do it and being ABLE to do it is worth it for sure. Even if I go out and buy 5000 factory new cases and call it good I think having the stuff and the ability to form your own is worth it for sure.

All of my brass has been home rolled. The key is selecting the brass. Follow the recommendations in this thread.
viewtopic.php?f=141&t=88599
And I recommend sorting the brass by brand when converting, gives more consistent results.
Also, get the Sheridan slotted case gauge. https://www.zepreloading.com/store/c1/F ... ducts.html

I have made my own for a long time and even have some YT videos about the method I put together. I found some time ago that using the Lee collet die on newly formed brass improves the quality aka accuracy considerably. There is a time commitment to making your own and lots of folks will make it for you, but having the process locked down to be self sufficient is a worthy skill. There is, however, no replacement for high quality purpose made brass with respect to accuracy.

Being able to make your own brass from the most common rifle cartridge in America is one of the many pro points to the 300 blackout cartridge.

TTF